IO-APIC
IO-APIC (I/O Advanced Programmable Interrupt Controller) is an Intel architecture for dealing with interrupts in multi-processor computer systems. It is implemented by the Intel 82093AA chip and found on all Intel SMP CPU boards.It is one of several attempts to solve IRQ problems; it should not be confused with ACPI.
It can be a cause of system failure, as some versions of some operating systems do not support it properly. If this is the case, disabling IO-APIC may cure the problem. For Linux, try the 'noapic' kernel parameter; for FreeBSD, the 'hint.acpi.0.disabled' kernel environment variable.
In Linux, problems with IO-APIC are one of several causes of error messages concerning "spurious 8259A interrupt: IRQ7."
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